Derived terms

Pharmacology is the study of how drugs interact with living
organisms to produce a change in function. If substances have
medicinal properties,
they are considered pharmaceuticals. The field encompasses drug composition and properties,
interactions,
toxicology, therapy,
and medical applications and antipathogenic capabilities.
Pharmacology is not synonymous with pharmacy, which is the name
used for a profession. Though in common usage the two terms are
confused at times. Pharmacology deals with how drugs interact
within biological systems to affect function, while pharmacy is a
medical science concerned with the safe and effective use of
medicines.

The origins of clinical
pharmacology date back to the Middle Ages
in Avicenna's
The Canon of Medicine, Peter of
Spain's Commentary on Isaac, and John of St Amand's Commentary
on the Antedotary of Nicholas. Pharmacology as a scientific
discipline did not further advance until the mid-19th century amid
the great biomedical resurgence of that period. Before the second
half of the nineteenth century, the remarkable potency and
specificity of the actions of drugs such as morphine, quinine and digitalis were explained
vaguely and with reference to extraordinary chemical powers and
affinities to certain organs or tissues. The first pharmacology
department was set up by Buchheim
in 1847, in recognition of the need to understand how therapeutic
drugs and poisons produced their effects.

Divisions

Pharmacology as a chemical science is practiced
by pharmacologists. Subdisciplines include

clinical pharmacology - the medical field of medication effects
on humans

Scientific background

The study of chemicals requires
intimate knowledge of the biological system affected. With the
knowledge of cell biology
and biochemistry
increasing, the field of pharmacology has also changed
substantially. It has become possible, through molecular analysis
of receptors,
to design chemicals that act on specific cellular signaling or
metabolic
pathways by affecting sites directly on cell-surface receptors
(which modulate and mediate cellular signaling pathways controlling
cellular function).

Metabolism
- Is the medication converted chemically inside the body, and into
which substances. Are these active? Could they be toxic?

Excretion - How
is the medication eliminated (through the bile, urine, breath,
skin)?

Medication is said to have a narrow or wide
therapeutic
index or therapeutic
window. This describes the ratio of desired effect to toxic
effect. A compound with a narrow therapeutic index (close to one)
exerts its desired effect at a dose close to its toxic dose. A
compound with a wide therapeutic index (greater than five) exerts
its desired effect at a dose substantially below its toxic dose.
Those with a narrow margin are more difficult to dose and
administer, and may require
therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycosideantibiotics). Most
anti-cancer drugs have a
narrow therapeutic margin: toxic side-effects are almost always
encountered at doses used to kill tumors.

If the structure of a medicine is altered
slightly, this will slightly alter the medicine's properties. This
means when a useful activity has been identified, chemists will
make many similar compounds called analogues, to attempt and
maximise the beneficial effects. This development phase can take up
to 3 years and is expensive.

These new analogues need to be developed. It
needs to be determined how safe the medicine is for human
consumption, its stability in the human body and the best form for
dispensing, like tablet or aerosol. After extensive testing, which
can take up to 6 years the new medicine is ready for marketing and
selling.

As a result of the long time required to develop
analogues and test a new medicine and the fact that of every 5000
potential new medicines typically only one will ever reach the open
market, this is an expensive way of doing things, costing millions
of dollars. To recoup this outlay pharmaceutical companies may do a
number of things:

Carefully research the demand for their potential new product
before spending an outlay of company funds.

Obtain a patent on the new medicine preventing other companies
from producing that medicine for a certain allocation of
time.

The drug must be found to be effective against the disease for
which it is seeking approval.

The drug must meet safety criteria by being subject to
extensive animal and controlled human testing.

Gaining FDA approval usually takes several years
to attain. Testing done on animals must be extensive and must
include several species to help in the evaluation of both the
effectiveness and toxicity of the drug. The dosage of any drug
approved for use is intended to fall within a range in which the
drug produces a therapeutic
effect or desired outcome.

Education

The study of pharmacology is offered in many
universities worldwide. Again, pharmacology education programs
differ from pharmacy programs. Students of pharmacology are trained
as researchers, studying the effects of substances in order to
better understand the mechanisms which might lead to new drug
discoveries for example. Whereas as pharmacy student will
eventually work in a pharmacy dispensing medications or some other
position focused on the patient, pharmacologist will typically work
within a laboratory setting.

Some higher educational institutions combine
pharmacology and toxicology into a single program as does Michigan
State University. Michigan State University offers PhD training
in Pharmacology & Toxicology with an optional Environmental
Toxicology specialization. They also offer a
Professional Science Masters in Integrative Pharmacology.